1. Field of the Invention
The present invention relates to rendering devices and, more specifically, to a rendering device which can be incorporated in a drive assistant device. In more detail, the rendering device generates a drive assistant image of an area around a vehicle based on images captured by image capture devices securely placed in the vehicle.
2. Description of the Background Art
The image capture devices 1001 to 1008 are directed in each different direction to cover the entire area around the vehicle Vur, and are responsible for image capturing. The resulting images are referred to as captured images S101 to S108, which are stored in the image memories 1009 to 1016, respectively. From several specific captured images stored in any predetermined image memory among those 1009 to 1016, the image processing part 1017 partially cuts out any required part. The parts are stitched together to have a single surrounding image S200 (see FIG. 19). The surrounding image S200 is then displayed on the display device 1018.
The image capture devices 1001 to 1008 are directed in each different direction to cover the entire area around the vehicle Vur, and have charge of image capturing. The resulting images are referred to as captured images S101 to S108, which are stored in the image memories 1009 to 1016, respectively. From several specific captured images stored in any predetermined image memory among those 1009 to 1016, the image processing part 1017 partially cuts out any required part. The parts are stitched together to have a single surrounding image S200 (see FIG. 19). The surrounding image S200 is then displayed on the display device 1018.
Here, FIG. 19 shows an example of the surrounding image S200 generated by the image processing part 1017 in the above manner. In FIG. 19, the surrounding image S200 is composed of partial images S106′ to S108′, which are respectively cut out from the captured images S106 to S108. The partial image S108′ occupies a left-side region R2001 of the surrounding image S200. The partial images S107′ and S106′ occupy, respectively, a center region R2002 and a right-side region R2003 of the surrounding image S200. Here, for convenience, a boundary between the left-side region R2001 and the center region R2002 is referred to as a seam boundary B2001, which is denoted by a dotted line in FIG. 19.
As another example of the conventional drive assistant device, there is a device for monitoring a surrounding area of a vehicle disclosed in International Publication WO00-07373. The monitoring device carries a plurality of image capture devices, which are responsible for image capturing of each different region and cover the entire region around the vehicle. The resulting images captured by those image capture devices are now referred to as captured images, and each show the region around the vehicle for which it is responsible.
Based on those captured images, the monitoring device generates a surrounding image showing the vehicle and the area therearound viewed from above. To be more specific, since the captured images are the ones viewed from the image capture devices, the viewpoint conversion processing is carried out to generate the surrounding image viewed from the above. In the above viewpoint conversion processing, every object in the captured images is assumed as lying on the road surface to reduce the CPU load. The objects are projected on to the road surface to generate spatial data, which is utilized to generate one surrounding image by stitching a plurality of captured images together.
The above two image drive assistant devices both bear problems. Described first is the problem unsolved by the first-mentioned drive assistant device. The surrounding image S200 thus derived by the conventional drive assistant device bears a problem of image distortion, which is evident especially on the seam boundary B2001. Generally, there are various many objects (typically, walls and other vehicles) around the vehicle Vur, and thus those often locate on the seam boundary B2001 in the surrounding image S200. Assuming here is a case where a wall W200 is located on the seam boundary B2001 as shown in FIG. 19. In this case, the wall W200 appears both in the captured images S107 and S108. Since the image capture devices 1007 and 1008 are mounted in each different position, the wall W200 is viewed from different directions. Therefore, the wall W200 resultantly looks distorted in the surrounding image S200, especially in the vicinity of the seam boundary B2001. Therefore, the surrounding image S200 displayed on the display device 1018 problematically causes a driver of the vehicle to feel strange.
The problem unsolved by the above-mentioned monitoring device is not displaying an image of an area that correctly resembles the area. This problem is evident especially on the surrounding image wherein objects displayed in the image do not correctly resemble corresponding objects in the surrounding area. More specifically, as shown in FIG. 20A, presumably, placed on a road surface Frd is an object B, a cross section of which is reverse “L” shaped. In the above viewpoint conversion processing, as shown in FIG. 20B, the object B is viewed from viewpoints of image capture devices 2001 and 2002, and projected onto the road surface Frd therefrom. As a result, virtual objects B′ and B″ are obtained. Therefore, the spatial data resultantly generated from the captured image derived by the image capture device 2001 includes the virtual object B′ as the object B, while the spatial data from the captured image 2002 includes the virtual object B″.
By utilizing such two spatial data, the monitoring device generates one surrounding image. The issue here is, since the two spatial data include the virtual objects B′ and B″ each have different shape, the monitoring device problematically cannot correctly render the object B, and the resulting object B is not correctly displayed. As a result, the surrounding image generated by such monitoring device causes the driver to feel strange.